This invention relates to an outboard motor and more particularly to an improved accessory drive for an outboard motor.
As is well known, the power head of an outboard motor is quite compact in nature and does not afford a large amount of space for the powering engine and numerous accessories which may be driven by the engine. Some of these accessories perform functions in connection with the actual engine operation and other accessories may be utilized for other purposes which may include engine operation. However, the driving and positioning of these accessories is quite complicated by the small space that is available within the power head.
In order to improve the performance of the engines employed in outboard motors, it has been proposed to utilize direct cylinder fuel injection. Such direct injection systems generally require higher pressure pumps than utilized with normal manifold type fuel injection systems. This is because the fuel must be injected at a pressure higher than that in the combustion chamber which is considerably higher than atmospheric pressure present in the induction systems where conventional manifold injectors inject.
Therefore, in addition to all of the other conventional or desirable optional accessories, it is necessary to provide and drive a high pressure pump to elevate the fuel to the pressure required by the injectors. Because of the high pressures required, the high pressure pump generally requires an engine drive rather than electrically operated fuel pump, as may be employed with lower pressure fuel injection system.
This generally requires the driving of the high pressure pump directly from the engine crankshaft, which already is employed for driving other accessories, as aforenoted. Furthermore, because of the vertical disposition of the crankshaft in outboard motor applications, the placement of the accessory drives presents problems not present in more conventional engine applications where the engine output shaft rotates about a horizontal axis.
Generally, it is the practice to position the flywheel for the engine at the upper end of the crankshaft so as to facilitate starting and location of the starter motor and other components. However, this leaves little room for additional accessory drives such as a drive for a high pressure fuel pump for a fuel injection system. Also, this latter accessory may be an optional accessory depending upon the specific engine and injection system utilized.
That is, a same basic engine configuration may utilize in some applications with direct cylinder injection and in other applications having manifold injection. Thus, it is desirable if the same engine crankshaft and flywheel assembly can be utilized by both specific engine applications. However, this gives rise to the problem in positioning of the high pressure pump drive for the direct fuel injected version of the engine.
It is, therefore, a principal object of this invention to provide an improved accessory drive for an outboard motor.
It is a further object of this invention to provide an improved high pressure fuel pump drive for an outboard motor that is driven off of the crankshaft.
It is a yet further object of the invention to provide an improved and compact flexible transmitter drive arrangement for engine accessories with engines utilized in outboard motors and wherein certain of the accessories are driven above the flywheel while others are driven below the flywheel.